1. Field of the Invention
The present invention relates to a friction plate for a wet clutch, and particularly, to an improvement in a friction plate for a wet clutch, which is comprised of a core plate, and friction members bonded to opposite sides of the core plate, the friction members being provided with a plurality of first oil grooves permitting the communication between inner and outer circumferential edges of the friction member, and a plurality of second oil grooves each permitting the communications between intermediate portions of adjacent first oil grooves, each of the first oil grooves being disposed in such a manner that it is inclined in a circumferential direction of the core plate at a given angle with respect to a line of radius passing through a radially inner end of the first oil groove.
2. Description of the Related Art
Such a friction plate for a wet clutch is already known, as disclosed, f or example, in Japanese Patent Application Laid-open No. 4-211729, and an essential portion of such friction plate is shown in FIG. 8. In FIG. 8, reference numeral 020 is a plate core; 021 is a friction member; 022 is a first oil groove; and 023 is a second groove.
In use of such friction plate for the wet clutch, when the clutch is turned off, cooling oil, during passing through the first oil groove, is diverted into the second oil groove, thereby cooling all the friction members, and preventing the dragging that may cause due to the viscosity of the oil.
However, the second oil grooves 023 in the conventional friction plate are arranged on the same circumference concentric with the core plate 020, as shown in FIG. 8. Therefore, when the friction plate and its adjacent clutch plate are rotated relative to each other by turning off the clutch, a pumping effect for positively feeding the oil in a radial direction is not generated in the second oil grooves 023, and it is difficult to permit a large amount of oil to be passed, particularly, through the second oil grooves.